XIII_rocks posted...
When you have closed off a section to be cleaned, MOVING CHAIRS OUT OF THE WAY TO SIT THERE when you have just walked past SEVERAL EMPTY SEATS.
Rage.
I have a worse seat-related one.
The brewery store I worked in had a tall shelf behind the counter for t-shirts and clothing that required the use of a little step ladder. One day, a customer just walks behind the register, grabs the step ladder, hauls it into the middle of the store floor and sits down, oblivious to the many irritated people surrounding him.